A FD (Full Duplex) technology allows signal sending and receiving to be simultaneously performed by using carriers with a same frequency. The full duplex technology is a combination of advantages of a TDD (Time Division Duplexing) technology and a FDD (Frequency Division Duplexing) technology, and theoretically, can double spectrum utilization. However, in actual application, when the full duplex technology is used, relatively high co-channel interference is generated by a transmit antenna and a receive antenna. The co-channel interference includes near-end interference and far-end transmission interference. The near-end interference is caused by a local-end transmit antenna on a local-end receive antenna. The far-end interference is caused after a signal sent by a local-end transmit antenna is reflected when being blocked by an obstacle and is received by the local-end receive antenna. A channel of the near-end interference and a channel of the far-end transmission interference form an overall interference channel of a full duplex system. The overall interference channel has features that a channel length is large and interference signal energy is mainly centralized near each reflection point. As shown in FIG. 1, FIG. 1 is a schematic diagram of a scenario in which a transmit antenna and a receive antenna generate co-channel interference according to the conventional art. A station A is used as an example. A signal received by a receive antenna of the station A is r=S1I*h1,0+I*h1,1+I*h1,2+ . . . +I*h1,M. h1,0 is an interference channel of near-end interference, h1,1, h1,2, . . . , h1,M respectively indicate channels of far-end transmission interference, and * indicates a convolution. Each sub-interference channel is a multipath interference channel, that is, h1,i=[h1,i,0, h1,i,1, h1,i,2, . . . , h1,i,N], and i=0, 1, 2, . . . , M. S1 is a wanted signal, and I indicates an interference signal sent by a local-end transmit antenna. To ensure reliable sending and receiving of signals, co-channel interference cancellation is a key point of the full duplex technology.
Currently, co-channel interference cancellation solutions are as follows: 1. An estimated value of an overall interference channel is obtained by performing estimation on the overall interference channel, and then filtering processing is performed on a reference interference signal by using the estimated value as a filter coefficient, so as to restore an equi-amplitude phase-inverted signal of a received interference signal. In this solution, to obtain the estimated value of the overall interference channel through estimation, a sent sequence length used for the estimation of the overall interference channel is at least greater than a length of the overall interference channel. Spectrum overheads are high, and spectrum utilization is greatly reduced. 2. A frequency domain balancing solution: In this solution, to balance an overall interference channel with a large channel length, a protection interval length that needs to be inserted is at least of a channel length magnitude. Spectrum overheads are high, and spectrum utilization is greatly reduced. It can be learned that, the spectrum overheads are high in the current co-channel interference cancellation solutions.